1. Field of the Invention
The present invention generally relates to a safety binding assembly, including a movable boot supporting plate, for use with skis which is adapted to maintain, in a laterally releasable fashion, one of the ends of a boot with respect to a ski; and, more specifically, to a safety binding for a ski which is adapted to retain either the front of the boot, or the rear, but which is however more particularly adapted to retain the front. The binding is further adapted to facilitate freeing a ski boot from a ski by lateral displacement when a force is exerted on the binding by the boot.
2. Description of Background Materials and Relevant Information
A safety binding such as that described herein assures the safety of a skier by responding, through its lateral release, to excessive torsional forces at the level of the leg of the skier. Presently available safety bindings employing a lateral release mechanism have a certain number of disadvantages, particularly when a torsional fall of the skier is combined with a frontward fall. For example, when movement occurs that causes the weight of the skier to move forwardly, the bottom of the sole of the boot of the skier is pressed against the ski with a substantial force directed downwardly towards the ski. This serves to create, between the bottom of the sole and the support surface therefore, a substantial frictional force opposing the lateral displacement of the boot; conventional lateral release safety bindings have exhibited difficulty in overcoming such frictional force.
A solution has long been sought to the problem of safety bindings of the lateral release type in order to provide a binding which maintains the boot substantially immobile so as to permit normal skiing in a stable maintenance position of the boot, substantially along the vertical longitudinal median plane of the binding; yet which is surely laterally releasable, as necessary, by reducing to a minimum the friction between the sole of the boot and the upper surface of the ski.
It has thus been previously proposed to glue to the surface of the ski a plate made of an anti-friction material, such as is described in French Patent No. 2,092,844. However, the cleats which may be provided under the sole of a ski boot act to considerably increase the friction that exists between the sole of the ski boot and the top of the ski, and often render the separation of the two uncontrollable.
To further diminish friction between the boot sole and the ski, it has been proposed to insert between the sole of the boot and the upper surface of the ski a movable support plate which is adapted to be laterally displaced with the boot. In such a system, sliding between the movable plate and the ski should not be hindered by excessive friction or by the cleats of the boot.
One solution, described in Document W085/03,451, consists of utilizing plates affixed to the binding. However, in this first case, if ice forms between the plate and the ski, the binding will be blocked, or at least a very substantial disturbance to its continued operation will occur.
A second solution, described in Swiss Patent No. 490,871, consists of providing a rotatable plate, positioned on the upper surface of the ski, which is biased so as to return to a central position; this action is actuated by a recentering spring. The disadvantage of this second solution is that during release of the binding, the boot pivots the plate against the energy of its recentering spring. This energy adds to the energy of the binding, and increases the force which the leg must exert to result in the release of the binding.